71B MultiMod: MEMORY LOST when changing batteries?

[teenix]

(04-21-2021 02:24 PM)Dave Britten Wrote:  Yeah, I was wondering if it might be a stray pull-up/down somewhere, but I don't know nearly enough about electronics engineering to go much further than that.

It is only a guess as I don't know much about the project, but the PIC IO pins have protection diodes from each pin to Vcc and one to Gnd. If the PIC is powered down, but an IO pin has (say) 5V applied, the 5V will go through the diode and out of the Vcc pin to the circuits power rail.

cheers

Tony